All three branches of the federal government are now fully engaged in an escalating battle over the future of same-sex marriage in the US.

Three weeks ago President Obama urged Congress to repeal the federal Defense of Marriage Act (DOMA) after concluding that the law is unconstitutional. In response, more than 100 members of the House of Representative on Wednesday introduced a bill to repeal the 1996 ban on federal recognition of same-sex marriage.

“The time has come for the federal government to recognize that every American family deserves all of the legal protections afforded to couples who are married under state law,” said Sen. Patrick Leahy (D) of Vermont. “This is a question of basic civil rights.”

While the previous Congress voted to repeal the military’s “don’t ask, don’t tell” policy banning gay men and women from serving openly, the current Congress is unlikely to do the same with DOMA. But that didn’t dampen the enthusiasm of repeal advocates.

In addition to repealing DOMA, the new law would ensure that same-sex couples married under state laws would qualify for the same level of federal benefits available to heterosexual married couples.

Republicans mount a defense

The repeal campaign comes in sharp contrast to the efforts of the Republican leadership in the House. Last week, Speaker John Boehner said that in light of the president’s conclusion that DOMA was unconstitutional he would direct the House counsel to undertake the legal defense of the law and replace Justice Department lawyers in pending federal court challenges.

“This action by the House will ensure that this law’s constitutionality is decided by the courts, rather than by the president unilaterally,” Boehner said at the time.

Two other cases were filed in Connecticut and New York. It is those two cases that prompted a reassessment of the Obama administration’s defense of DOMA.

While government lawyers had defended the law in Boston, where earlier decisions established a legal precedent favoring upholding the law, no such precedent exists in the Second US Circuit Court of Appeals, which covers New York and Connecticut.

Recognizing this distinction, both the president and Attorney General Eric Holder concluded that government lawyers were no longer bound to defend the statute.

The administration says it will continue to enforce DOMA, but that government lawyers will no longer defend the statute in legal challenges.

In addition to the DOMA lawsuits, a major appeal is pending in California to determine whether same-sex couples have a right under the US Constitution to marry.

Legal analysts expect some or all of these same-sex marriage cases to eventually work their way up to the US Supreme Court.

In addition, four states recognize same-sex marriages performed in other states or jurisdictions. They are Maryland, New York, Rhode Island, and New Mexico.

DOMA allows states to ignore the legal effect of same-sex marriages performed under the law of another state. In addition, the federal statute defines marriage as a legal union between one man and one woman.

Eligibility for federal rights, benefits

The definition is important because it sets eligibility for more than 1,100 federal laws, programs, entitlements, rights, and benefits.

Proponents of the law say it is necessary to prevent erosion of the traditional concept of marriage as a permanent relationship between a man and a woman to encourage procreation and child rearing in a stable home environment.

Opponents say the measure has its roots in antigay bigotry and hatred. They say same-sex couples are just as capable of providing a loving and stable home life for children as heterosexual couples.

“The administration’s decision not to defend DOMA intensifies the urgent need to repeal this discriminatory law,” said Rep. Tammy Baldwin (D) of Wisconsin. “All legally married couples should have the same federal rights, obligations, and recognition, regardless of their sexual orientation.”

Among the legal challenges to DOMA, is a lawsuit filed in New York by Edith “Edie” Windsor, a resident of New York City. She spent 44 years with her partner, Thea Spyer, until Ms. Spyer’s death two years ago. Although they were legally married in Canada, the federal government, citing DOMA, did not recognize the marriage for purposes of US tax law.

Windsor was ordered to pay a $363,000 estate tax that she would not have owed the federal government had she been married to a man.

“All marriages should be treated equally in the eyes of the law,” she said.